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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        var year = 0;
        year = parseInt(window.prompt('请输入一个年份：'));
        if((year%4 ==0) && (year%100 !=0) || year % 400 == 0){
            document.write(year+'年是闰年');
        }else{
            document.write(year+'年是平年');
        }
    </script>
</body>
</html>